Clang should not generate calls to llvm.pow.* intrinsics.

Instead, it should generate calls to the pow* library functions, which
get found within the pexe.

This is a LOCALMOD for now, but I'm working on a more generic solution
that can be upstreamed to Clang.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3513
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/18135002

2 files changed, 13 insertions, 15 deletions

diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index 9e09131a53..7f1709e10f 100644
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -1293,14 +1293,11 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
   case Builtin::BIpow:
   case Builtin::BIpowf:
   case Builtin::BIpowl: {
-    // Rewrite sqrt to intrinsic if allowed.
-    if (!FD->hasAttr<ConstAttr>())
-      break;
-    Value *Base = EmitScalarExpr(E->getArg(0));
-    Value *Exponent = EmitScalarExpr(E->getArg(1));
-    llvm::Type *ArgType = Base->getType();
-    Value *F = CGM.getIntrinsic(Intrinsic::pow, ArgType);
-    return RValue::get(Builder.CreateCall2(F, Base, Exponent));
+    // LOCALMOD: For PNACl we don't want pow* calls to ever turn into
+    // intrinsics. We want them to be resolved vs. the newlib implementation
+    // within the pexe during bitcode linking.
+    // TODO(eliben): upstream this
+    break;
   }
 
   case Builtin::BIfma:
diff --git a/test/CodeGen/libcalls.c b/test/CodeGen/libcalls.c
index 8f8e18226a..87e0592337 100644
--- a/test/CodeGen/libcalls.c
+++ b/test/CodeGen/libcalls.c
@@ -31,25 +31,27 @@ void test_sqrt(float a0, double a1, long double a2) {
 // CHECK-YES: define void @test_pow
 // CHECK-NO: define void @test_pow
 void test_pow(float a0, double a1, long double a2) {
+  // LOCALMOD: for PNaCl we generate lib calls and not intrinsics, even without
+  // errno. For more details see the LOCALMOD in lib/CodeGen/CGBuiltin.cpp
   // CHECK-YES: call float @powf
-  // CHECK-NO: call float @llvm.pow.f32
+  // CHECK-NO: call float @powf
   float l0 = powf(a0, a0);
 
   // CHECK-YES: call double @pow
-  // CHECK-NO: call double @llvm.pow.f64
+  // CHECK-NO: call double @pow
   double l1 = pow(a1, a1);
 
   // CHECK-YES: call x86_fp80 @powl
-  // CHECK-NO: call x86_fp80 @llvm.pow.f80
+  // CHECK-NO: call x86_fp80 @powl
   long double l2 = powl(a2, a2);
 }
 
 // CHECK-YES: declare float @powf(float, float)
 // CHECK-YES: declare double @pow(double, double)
 // CHECK-YES: declare x86_fp80 @powl(x86_fp80, x86_fp80)
-// CHECK-NO: declare float @llvm.pow.f32(float, float) [[NUW_RO:#[0-9]+]]
-// CHECK-NO: declare double @llvm.pow.f64(double, double) [[NUW_RO]]
-// CHECK-NO: declare x86_fp80 @llvm.pow.f80(x86_fp80, x86_fp80) [[NUW_RO]]
+// CHECK-NO: declare float @powf(float, float)
+// CHECK-NO: declare double @pow(double, double)
+// CHECK-NO: declare x86_fp80 @powl(x86_fp80, x86_fp80)
 
 // CHECK-YES: define void @test_fma
 // CHECK-NO: define void @test_fma
@@ -122,4 +124,3 @@ void test_builtins(double d, float f, long double ld) {
 // CHECK-YES: attributes [[NUW_RN]] = { nounwind readnone }
 
 // CHECK-NO: attributes [[NUW_RN]] = { nounwind readnone{{.*}} }
-// CHECK-NO: attributes [[NUW_RO]] = { nounwind readonly }